Implementation for central data handling within a Multi-Instrument Suite

Abstract

The Magnetospheric Multiscale (MMS) observatory includes an Instrument Suite (IS) consisting of eight instruments providing various types of data. The science data must be stored for later downlink, trigger data processed in order to determine quality of the stored science data, bent pipe data routed to other instruments, and housekeeping forwarded to the spacecraft avionics for health and status. In addition, commands from the Science Operations Center via the spacecraft avionics must be properly processed and forwarded to the designated instrument. In order to properly handle and process the large amount of data associated with these instruments, Southwest Research Institute (SwRI) developed the Central Instrument Data Processor (CIDP). The CIDP utilizes the unique Consultative Committee for Space Data Systems (CCSDS) Application Process Identifier (APID) assigned to each packet within the system for steering the packet to the proper destination. The parallel handling of data from the eight instruments makes the steering function a perfect candidate for implementation in hardware. For science data storage, the CIDP employs a mass memory design based on commercial flash technology. With the limited number of writes and potential for memory cells to go bad, metrics for the flash must be monitored and maintained to ensure reliable storage. The data is then downlinked using the CCSDS File Delivery Protocol (CFDP). Hardware implementations of the flash interface and CFDP protocol greatly relieve the responsibilities on flight software. This paper provides an architectural view into the CIDP data handling functions from receipt to downlink. Emphasis is placed on the hardware designs incorporated to increase capability while decreasing the burden on flight software. It also identifies bottlenecks in the system, and addresses how these could be alleviated to improve overall throughput.